584 THE REPRODUCTIVE FUNCTIONS. 



moving away from the other, and beginning its 

 independent existence. This mode of separation 

 is illustrated by Fig. 462, representing the suc- 

 cessive changes of form during its progress. 



462 



463 



In this animalcule the division is transverse, but 

 in others, for example in the Voi'ticella, (as 

 shown in Fig. 463), and in most of the larger 

 species, the line of separation is longitudinal. 

 Each animalcule, thus formed by the subdivision 

 of its predecessor, soon grows to the size which 

 again determines a further spontaneous subdivi- 

 sion into two other animalcules ; these, in course 

 of time, themselves undergo the same process, 

 and so on, to an indefinite extent. The most 

 singular circumstance attending this mode of 

 multiplication is that it is impossible to pro- 

 nounce which of the new individuals thus 

 formed out of a single one should be regarded as 

 the parent, and which as the offspring ; for they 

 are both of equal size. Unless, therefore, we 

 consider the separation of the parts of the parent 

 animal to constitute the close of its individual 

 existence, we must recognise an unbroken conti- 



